The invention relates to a deformation measuring device for measuring the torque of a cylindrical shaft, comprising a sensor which can be mounted on the shaft and on which there is arranged at least one transducer for converting a torque-dependent deformation of the shaft into a signal which can be evaluated and displayed.
Deformation measuring devices are known per se. For example, they are known from the article "Mikrorechnergestfitzte Werkzeuguberwachung auf der Basis von Dehhnungsmessungen an Drehmachinen", Stange, B, Feingeratetechnik 36, 1987, Band 10, pp. 463 to 465. Deformation measuring devices of this kind comprise an area of reduced cross-section where, for example strain gauges are provided. A comparatively greater deformation occurs in the area of reduced cross-section. Only deformation in the plane of the sensor or the bending of a beam can be measured. Deformation measuring devices of this kind which are suitable for measuring the bending of a beam, therefore, are not suitable for torque measurement, that is to say measurement of the deformation of a shaft by torsion.
For torque measurement of a cylindrical shaft, for example, the leaflet "Drehmoment-Messung", Dr. Steiger, Mohilo+Co GmbH, Baumwasenstr. 5, D-7060 Schorndoff, page 11, describes a deformation measuring device which is referred to as a DMS-Aufnehmer FN. This deformation measuring device utilizes frequency-modulated signal transmission. In a housing there is accommodated a journalled shaft. This shaft comprises a torsion zone in the form of a constricted area in which strain gauges are provided in a bridge circuit. The bridge converts a torque between two shafts into a proportional electric signal. At the drive end of the shaft of the deformation measuring device there are provided two transformer coils for signal transmission. The larger coil serves to feed the electronic circuitry in the rotating shaft, whereas the smaller coil transmits the measurement signal from the shaft to the housing. The electronic evaluation circuitry is accommodated in a connection box of the housing.